If you're not ready to swim the English Channel or tackle a trek to the North Pole but are up to rafting or hiking the Grand Canyon, here are five other active adventures. All require advance work on your part -- both physical training and mental prep.

Hiking the Inca Trail in Peru. Because independent hikes aren't permitted -- you have to go with an organized group -- you have to be able to keep up with a pack, which usually allots about four days to hike the trail from Cuzco to Machu Picchu. Focus on cardiovascular workouts, especially stair work, to prepare. "You will be glad later when you are literally climbing up and down thousands of ancient steps," trekker Tim Leffel writes on Backcountry.com (www.backcountry.com). Before the hike, allow your body to acclimate to the altitude for a day or two before hitting the trail. Bring an atltitude sickness preventative along, just in case.

Skiing Jackson Hole. There are many mountains in the world, but few have as many expert slopes as Jackson Hole, Wyo. Fifty percent of the slopes are for advanced skiers (not counting the many unofficial trails). One to conquer is Corbet's Couloir, which includes a 20-foot jump inside a steep, 10-foot-wide chute. To ready yourself, keep taking lessons no matter how skilled you are -- and all the better if you can find someone who's familiar with Jackson Hole's slopes. Study the techniques of experts such as Warren Smith through DVDs, ski magazines and Web sites. Off the mountain, focus training on flexibility.

Surfing the North Shore of Hawaii. Among the hardest surf spots in the world, the North Shore of Oahu -- in particular Waimea Beach and the Banzai Pipeline at 'Ehukai Beach -- can have monstrous waves exceeding 20 feet between October and February. Even the most skilled surfers are challenged.

This is where serious studying can come in handy. Read surf Web sites, such as professional surfer Taj Burrow's Surfwithtaj.com (www.surfwithtaj.com), for tips. Build upper-body strength, especially in your shoulders, to aid in paddling. And spend as much time as possible in the water, building up to more-serious surf each time.

Climbing Mount Kilimanjaro. Ascending this 19,340-foot mountain doesn't involve ropes, snap links and other accouterments of the hard-core mountain climb. Essentially the Tanzanian ascent is a long, thin-aired walk -- it can easily take you a week or more -- requiring strong legs and loads of stamina. The best preparation for hiking mountains is to ... well, hike a mountain, according to the Web site UltimateKilimanjaro.com (www.ultimatekilimanjaro.com). Train in the hiking boots and day pack you plan to use on the trip. Long-distance walking can build stamina. And as with the Inca Trail, you must prepare for the thin air and sickness it could provoke.

Rafting the Zambezi River. Considered the wildest river in the world by rafting enthusiasts, the Zambezi, below Victoria Falls in Zimbabwe and Zambia, is a Grade 5 river. This means there are violent rapids and steep drops. Before you go, get up to speed on basic first aid, strengthen your swimming abilities (inevitably, you'll get flipped out of the raft) and work on conditioning and stamina, as there can be steep climbs out of the gorge at the end of the trip, according to the Web site of the Zambezi Safari and Travel Co. (www.zambezi.com).